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Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

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  • Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

    Im going to look at a boat this weekend. I can't find any info on this boat. The guy couldnt send me any pics so I can't share those. I'll check overall condition. the floor, and transom best I can. (ill bring a screwdriver to tap the back).
    Any pro's or cons with I/O? or things to look for?

    Heres what he told me
    "1979 18 ft V hull Thompson boat. I'm selling cause in the spring I'm upgrading bought as a project boat. Stuck over a grand in the motor. But now runs amazing. These are the things all redone
    2new solenoids
    All wiring brand new
    Spark plugs
    Carb
    Starter
    All boots replaced
    Water pump
    Ripped old seats out bought replace ments
    Motor cover completely redone
    Complete tune up
    New battery
    Motor tilt
    New tires on trailer
    Water pump

    Only thing that needs to be fixed is the speedometer gauge doesn't work and one of the trailer lights needs to be replaced. Boat runs great inboard outboard 4 cylinder merc cruiser 180hp with trailer."
    CrankyBaits Custom Painted Lures

    1981 Sylvan Sportster 16' 1985 Evinrude 70 hp


  • #2
    Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

    Without pictures it's hard to guess ... and without actually seeing it, it's really hard to know.

    Here's my concerns (right off the bat): I don't think the seller knows what they really have. A 4cyl 180HP doesn't sound right. Even worse, I'll bet that will turn out to be the dreaded Mercruiser 470.

    It all just sounds a little weird.

    What other choices to you have?
    ---------

    Murfreesboro, Tennessee

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    • #3
      Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

      So far, ive bought 2 boats in my lifetime. Both times they got the year of the boat and motor wrong. the last one even got the HP wrong when talking to him. even though its printed in big numbers on the motor.

      Im expecting the same in this instance.
      Im assuming this is what it is http://www.fiberglassics.com/wiki/im...bulletin79.jpg

      I know NOTHING about I/O. What should I look for in terms of good models, bad models, or obvious issues I can see.
      CrankyBaits Custom Painted Lures

      1981 Sylvan Sportster 16' 1985 Evinrude 70 hp

      Comment



      • #4
        Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

        The best thing you can do is demand a test ride. You probably won't get one this time of year but that's the best thing you can do. Short of that, check every inch of that deck to be sure there's no spring or mush in it. Likewise the transom needs to be stressed by trying to flex the outdrive (it shouldn't). Look for rust on the outside of the engine and note how high it goes if there is any. It's had water that high in there. Pull the dipstick and look for at the oil for evidence of water contamination. If it's a salt water boat look hard at the exhaust manifold and the riser for signs of impending failure. Look underneath the engine for stains or leaks.

        And BTW: the GM built 4 cylinder Mercruiser engine is 3 liters/181 ci and develops between 120-140 HP depending on the year.
        Jay Hanig
        Topsail Beach, NC USA
        1985 Galaxy 176 Bowrider
        "No Good Deed"

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        • #5
          Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

          I think you're going to find out it has the Mercruiser 470 motor in it which for me would be a non-starter. It was a problematic design and has a number of NLA parts. For I/O's you want Mercruiser or Volvo with Chevy based engines.
          1976 18' Starcraft SuperSport 90HP Evinrude
          Restoration thread http://forums.iboats.com/showthread.php?t=357767
          1966 16' Starcraft Jupiter 85HP Johnson
          Restoration thread http://forums.iboats.com/showthread.php?t=338633 sold

          Comment



          • #6
            Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

            Originally posted by rtpassini View Post
            I know NOTHING about I/O. What should I look for in terms of good models, bad models, or obvious issues I can see.
            Buyin' used you kinda' have to roll with the market, y'know?

            Not knowing exactly what you want to do on a boat (fish, ski, cruise, swim, etc.), where you're boating (Great Lakes, inland lakes) I took a quick spin through the CL listing I think that Larson you were looking at. With all of the offerings I saw, I would look at THIS boat or THIS boat.

            If you're lookin' specifically at I/O's (seems like you know a thing or two about OBs) - follow EZ's call. Chevy based Mercruiser or Volvo.
            ---------

            Murfreesboro, Tennessee

            Comment



            • #7
              Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

              Like the others said... if it's truely 180hp it's most likely the in-line 6. If that's the case, just run.
              If it's the 3.0 4 cyl (120 or 140hp) just check that there is no water in the oil.
              Check that the block is not cracked, or the exhaust log.
              Lift the outdrive all the way and check the belows for cracks or wear.
              The exhaust below doesn't mater much(the bottom one) but a tiny hole in the shift cable or drive belows can let a lot of water in the boat in very little time (this I know from personal experience).
              If these have been serviced then the gimbal bearing probably has been serviced as well.
              If the belows look as old as the boat then you know what else to look forward too!
              Check that the bottom bolts that hold the outside part of the outdrive to the inside transom plate are not loose as I have found is often the case when the transom goes soft.
              Good luck.
              P-T
              (Note: the word "carburetor" is a French word. In English it refers to the fuel mixture dispenser residing near a cylinder. However, you should be aware that the meaning of this word in the native French language is quite different. In French it means: "Don't mess with me".)

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              • #8
                Re: Thoughts? 79 Thompson 18' open bow 4 cyl merc cruiser

                Originally posted by Part-time View Post
                Like the others said... if it's truely 180hp it's most likely the in-line 6. If that's the case, just run.
                The in-line 6 isn't too bad. It's the big 4-cylinder you don't want. Most commonly called the Mercruiser 470 but also can be seen as 170, 190, 485 and 488. All are 3.7L 4 cylinders.
                1976 18' Starcraft SuperSport 90HP Evinrude
                Restoration thread http://forums.iboats.com/showthread.php?t=357767
                1966 16' Starcraft Jupiter 85HP Johnson
                Restoration thread http://forums.iboats.com/showthread.php?t=338633 sold

                Comment

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